Daiichi's Plexxikon goes after Novartis cancer med Tafinlar in BRAF patent suit

Novartis' Tafinlar won FDA approval after Roche launched its own BRAF inhibitor Zelboraf, but the Novartis med and its combo partner are bringing in more sales.

A small drug discovery outfit in California is challenging one of the world’s largest drugmakers in a patent dispute over a cancer drug reeling in considerable sales. After bringing Zelboraf to market with Roche, Plexxikon alleges a competitor from Novartis is stepping on its intellectual property.

The drug at issue is Novartis’ targeted cancer med Tafinlar, picked up as part of the Swiss drugmaker’s massive asset swap with GlaxoSmithKline. According to Plexxikon’s new lawsuit, GSK scientists acquired the knowledge they used to develop Tafinlar after consulting with Plexxikon’s team in potential partnership talks.

Those talks never materialized into a licensing deal, but the suit says GSK took information from those interactions and created a rival drug. Plexxikon instead teamed with Roche to develop and market Zelboraf, a competing drug in the same class that targets the BRAF V600E mutation.

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Plexxikon filed its patent applications way back in 2005 and later received a patent on “a class of selective BRAF kinase inhibitors which selectively bind to the BRAF kinase that results from the V600E mutation," according to the suit. The biotech says Novartis’ Tafinlar is in the class and continues to eat away at sales for Zelboraf.

Sales for Tafinlar and a combination partner, Mekinist, came in at $672 million last year. Zelboraf won the first FDA approval of the group back in 2011, but its sales haven't grown as quickly. Roche reported about $218 million in Zelboraf sales last year.

According to Plexxikon, which became a part of Daiichi Sankyo in a 2011 buyout, GSK filed its first patent application for the drug class in May 2008. The suit says there’s ”substantial evidence to suggest that GSK built” its med by “copying Plexxikon’s invention.”

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Because GSK sold the med to Novartis along with a host of other cancer assets, Plexxikon wants a court to issue an injunction and force Novartis to pay damages and royalties.

A Novartis spokesperson said the company doesn’t comment on ongoing litigation. Tafinlar nabbed its initial FDA approval in 2013 as a monotherapy; Novartis won a new nod for Tafinlar plus MEK inhibitor Mekinist in 2015 to treat patients with unresectable or metastatic melanoma who have the mutation. More recently, the combo picked up an FDA approval to treat patients with metastatic non-small cell lung cancer (NSCLC) who have the BRAF V600E mutation.

Zelboraf also won a combination approval in 2015, to treat melanoma alongside its own MEK inhibitor Cotellic. In a key clinical trial, adding Cotellic to Zelboraf boosted progression-free survival to a median of 12.3 months from 7.2 months for Zelboraf alone. And 65% of combo patients were alive 17 months after starting treatment, compared with 50% for the Zelboraf-only group.